1. Field of the Invention
The present invention relates generally to a semiconductor process, and more particularly, to a semiconductor process that forms at least a recess in a fin-shaped structure beside a gate structure with light spacer pull down.
2. Description of the Prior Art
With increasing miniaturization of semiconductor devices, various Fin-shaped field effect transistor (FinFET) devices have been developed. The Fin-shaped field effect transistor (FinFET) is advantageous for the following reasons. First, manufacturing processes of Fin-shaped field effect transistor (FinFET) devices are similar to traditional logic device processes, and thus are more compatible. In addition, since the three-dimensional structure of the FinFET increases the overlapping area between the gate and the fin, the channel region is controlled more effectively. This therefore reduces drain-induced barrier lowering (DIBL) effect and short channel effect. Moreover, the channel region is bigger for the same gate width. Therefore, the current between the source and the drain is increased.
In a current FinFET process, a gate structure (which may include a gate dielectric layer, a gate electrode located on the gate dielectric layer, a cap layer located on the gate electrode, and a spacer located beside the gate dielectric layer, the gate electrode and the cap layer) is formed on a substrate having at least a fin-shaped structure. Then, epitaxial layers are formed on the fin-shaped structure beside the gate structure. The epitaxial layers can be formed in a recess of the fin-shaped structure to enhance the carrier mobility of the gate channel.
However, during the formation of the recess of the fin-shaped structure (the fin recess process), the spacer beside the gate dielectric layer, the gate electrode and the cap layer may be partially removed by the etchant/chemical solvent in the etching/pre-clean steps in the conventional fin recess process, which may induce serious spacer pull down and cause the gate electrode to be exposed. Accordingly, a semiconductor process, more specifically a FinFET process including a fin recess process, which can improve the performances of the epitaxial layers and the reliability of semiconductor device, is needed in the industry.